1. Field of the Invention
This invention relates to a sectional form measuring apparatus for measuring sectional forms of an object to be measured.
2. Description of the Prior Art
A sectional form measuring apparatus for measuring sectional forms of the object by irradiating light to the object, detecting the light reflected from the surface of the object on a detector, and calculating a distance from the reference axis to the surface of the object according to the detection output has been proposed by the same inventors as this application in Japanese Patent Laid-Open No. 83606/1987.
According to the sectional form apparatus proposed as above, from the sectional form precisely with the human body as the object, data on a surface form of the human body is obtained, and thus women's underwear fitting well and rich in aesthetical sense can be designed according to the data.
Besides, in a medical field, a surface form of the backbone portion of a patient will be measured by means of the sectional form measuring apparatus relating to the aforementioned proposal, thereby diagnosing and examining scoliosis.
Further, with the airframe as a measuring object, a deformation of the surface of the airframe subjected to internal and external pressure differences will be determined on the sectional form measuring apparatus relating to the aforementioned proposal, thereby obtaining materials for design or secular change on the airframe.
In the sectional form measuring apparatus relating to the aforementioned proposal, a driving shaft in parallel with the reference axis as the center is mounted rotatably round the object disposed on an inspection bed with the reference axis as the shaft center. A plurality of high directional LED's 11 mw in output and 2.0 mm in beam dia., for example, are arrayed longitudinally of the driving shaft, and the construction is such that the light irradiated from a light source consisting of these LED's is incident successively on the surface of the measuring object at right angles to the reference axis.
The light reflected from the object surface is incident on the detector, and the detector is constructed to have the distance from a reference point to a light receiving point corresponding to a distance from a light emitting point of LED to an irradiated point of the object. Accordingly, a distance from the reference point to the light receiving point is measured on the detector, and thus a distance from the reference axis to the irradiated point of the object surface is obtainable through the aforementioned distance.
A sectional form of the object with the reference axis as the center is obtainable through the distance obtained as above.
In the above-described sectional form measuring apparatus proposed hitherto, a first problem is that there may be a case where the detector is not capable of receiving the light reflected from the object surface according to a surface form of the object.
FIG. 1 represents a measuring principle according to the prior art sectional form measuring apparatus described above, wherein a protrusion 3 is formed on the surface of a object 2 positioned on a reference axis 1. Consequently, on the surface of rotation with the reference axis 1 as the center, reflected lights from irradiated points P-2 to P-4 on the surface of the object 2 of focused lights from lenses 5-1 to 5-4 fixed to a plurality of light sources 4-1 to 4-4 disposed in parallel with the reference axis 1 respectively will be received by a detector 6. However, reflected light from an irradiated point P-1 is intercepted by the protrusion 3 and cannot be received by the detector 6.
Accordingly, in case sectional forms passing through the irradiated points P-1 to P-4 each at right angles to the reference axis 1 are measured by rotating a support 7 with the light sources 4-1 to 4-4 and the detector 6 mounted thereon round the measuring object 2, the sectional form passing through the irradiated point P-1 is not obtainable perfectly.
Then, a second problem is that a sectional form of the measuring object is obtained at every irradiated light from aforementioned each light source disposed along the driving shaft parallel with the reference axis, therefore a resolution of the measurement in the direction along the reference axis is proportional to an array density of the light sources.
Here, from using LED as a light source an outside diameter of one light source becomes 10 mm or so including a housing, and if measurement of a sectional form is carried out in a domain 300 mm away from the reference axis of the object, 31 sheets of sectional forms will be obtained at intervals of 10 mm along the reference axis.
However, in such portion as is abrupt in inclination of the surface of a measuring object, the resolution of measurement whereby sectional forms are obtainable at intervals of 10 mm along the reference axis is not sufficient to obtain sectional form data in required precision.
For example, in the case of a design of women's underwears mentioned hereinabove, if a surface form of the breast of the object is measured at intervals of 10 mm in the direction of reference axis, data obtainable therethrough is still not sufficient for designing a brassiere fitting well and rich in aesthetical sense.
A third problem refers to a biological sectional form measuring apparatus proposed hitherto for irradiating optical waves from the light sources 4-1 to 4-4 to a plural position on the reference axis at the same angle position around the reference axis at every unit rotational angle, wherein a measurement is not practiced at any positions between adjacent measuring points. That is, in the biological sectional form measuring apparatus proposed hitherto, a practical measurement of sectional forms is not carried out at any positions on the reference axis between adjacent measuring points measured at every unit rotational angle around the reference axis, and a space between data points on distance between the reference axis and the object surface obtained at adjacent measuring points is connected with a straight line to realize a sectional form of the object.
Accordingly, if there arises a striking change for some reason or other on the surface form of the object at position between the adjacent measuring points, then a change in the surface (sectional) form of the portion will be overlooked. As shown in FIG. 2 (A), for example, if there exists an abnormal protrusion 27 between measuring points c.sub.1, c.sub.2 of the object 2, a presence of the abnormal protrusion 27 cannot be confirmed as a practical measurement is not carried out at the portion. Accordingly, in order to measure precisely an actual surface form of the object without such oversight on the biological sectional form measuring apparatus proposed hitherto, a measuring point must be provided further between the adjacent measuring points.
Thus, a unit rotational angle around the reference axis must be set a little further, which may complicate the driving mechanism and require a long time for measurement, too.
Next, a fourth problem is that a surface (sectional) form pattern obtained through measurement does not indicate accurately a specific measuring position of the object therein at a glance.
For example, a presence of the curved backbone cannot be identified exactly in position from observing the pattern. Then, surface form patterns of an airframe which are shown in FIG. 3 (A), (B) and (C) are not indicative of the position of a joint 65 of the airframe of FIG. 4.
Thus, if, for example, a doctor detects a degree of curvature of the patient's backbone by touch for examination of scoliosis, it is not clarified whether the backbone corresponds in position on the surface form pattern. However, for diagnostic cure of scoliosis, it is necessary that a correlativity between the degree of the backbone curvature and the surface form pattern obtained through measurement is confirmed, and that a remedy is examined with reference to the surface form pattern and an effect of the cure is decided. It is therefore desirable that a presence of the backbone will be identified in position, at a glance, on the surface form pattern.
Then, in a pressure test of the airframe, it is of vital importance that a positional relation between the change arising on the airframe surface form and the joint 65 be secured for designing a pressure-withstanding airframe.
Consequently, it is desirable that the joint 65 be identified in position on the surface form pattern of the airframe obtained through measurement.
A further fifth problem is that since the light emitting elements (light sources) 4-1 to 4-4 and the detector 6 are disposed, as shown in FIG. 1, on the same line parallel with the reference axis 1, a height of the optical devices including light emitting elements (light sources) 4-1 to 4-4, lenses 5-1 to 5-4 and detector 6 becomes lengthy dimensionally, thus preventing miniaturization requirement. In case the number of light emitting elements is increased particularly for high resolution measurement to be carried out, a prior art system inevitably leaves a problem that the apparatus becomes large in size. Further, the detector is generally disposed on the same line as and also under the light emitting elements at a definite inclination to the horizontal plane, therefore in case the measuring object is the breast where the optical wave is irradiated to an upper portion of the breast, the reflected light is not incident on the detector, thus leading to impossibility of the measurement.